The present invention generally relates to a quadrant detector arrangement and, in particular, relates to one such quadrant detector arrangement having integral light channels.
Quadrant detectors are generally known in the art. Full quadrant detectors are frequently used to optically align a workpiece to a preselected position. For example, in setting up a mechanism, such as an optical bench, the bed of the mechanism can be aligned parallel with a reference plane by use of a precisely positioned quadrant detector disposed in the reference plane but removed from the bed of the mechanism. In such an operation, a mirror is affixed to the bed of the mechanism and, by measuring the relative tilt in the x and y directions with the quadrant detector, the bed can be precisely positioned with respect to the reference plane of the quadrant detector. In such an operation the quadrant detector is, effectively, operated as a null detector, i.e. the goal is to align the reflected light from the bed until each quadrant receives the same amount of reflected light.
Another use for quadrant detectors is the measurement of optical properties, such as astigmatism, of spherical lenses. In such an application, a lens to be measured is disposed so that the light reflected therefrom is directed onto the quadrant detector. The amount of light reflected from the lens is then determined as the lens is rotated. The variation of the light measured in each quadrant gives a measure of the aberration of the lens.
In general, in most quadrant detector arrangements, the apparatus used frequently includes beam splitting optics as well as various lenses. One significant drawback associated with the use of beam spitters is that only about one half of the original light signal is ultimately projected toward the workpiece. Hence, such arrangements generally require powerful light sources and/or relatively sensitive quadrant detector devices.
Consequently, it is highly desirable to provide a quadrant detector arrangement that overcomes the above-recited drawbacks of conventional quadrant detector arrangements.